Shown on the right is one of my Avo CT-160 portable valve testers. The
one in the pic is c.1962, which gives some idea of the durability and quality of these
In addition to the go/no-go facilities offered by testers, this one allows measurement
of anode current to be made with surprising accuracy. It allows allows mutual
conductance (gm) to be measured - this is invaluable for applications requiring matched
Different heater voltages are catered for, as are different anode and screen voltage,
all selected by clearly marked rotary switches.
Gas testing is available, which will give an idea of the amount of residual gas in a
tube, and will allow leaky seals to be detected before a "flash" occurs.
Also checks rectifiers and signal diodes to see what kind of shape they are in.
For instructions on how to use it, click here.
David Crittle has the calibration instructions on his site - you can read them
by clicking here.
||Filament, Insulation, cathode/heater leakage resistance to 25M ohms, gas,
current draw, mutual conductance.
||British 4/5/7/9 pin (B4/B5/B7/B7A/B9), P type base (8SC), International
Octal, Mazda Octal, UX4, UX5, UX6, UX7, American SM7, American loctal (B8B or B8G),
B9D, B8D, Hivac 4 pin (SM4), Hivac 5 pin (SM5), B7G (miniature), B9A (noval), B3G, 5AA and
7AA for Acorn valves, F8, B8A, B5A.
Two uncommitted clips which can be connected to top
cap or side cap connections.
||Selectable 105-120 in 5V steps, 175-250 in 5V steps @ 50-500Hz. AC.
||0.625, 1.25, 1.4, 2.0, 2.5, 3.0, 4.0, 4.5, 5.0, 5.7, 6.3, 7.5, 10, 11,
12.6, 13, 15, 16, 18, 20, 23, 25, 28, 30, 35, 40, 45, 48, 55, 70, 80, 117
||20, 40, 60, 75, 90, 100, 150, 200, 250, 300, 400
||20, 40, 60, 75, 90, 100, 125, 150, 200, 250, 300
||Continuously variable from 0 to -40V.
||Measures anode current up to 100mA, gm from 0-20mA/Vm, diode/rectifier
efficiency, short circuit protected.
||Oh yes, and it's portable!
If you are into other types of valve (tube) tester, check out Matts Tube Extravaganza as he has a whole page on Tube Testers.
Whilst on this subject, there is plenty of info on Hickock tube testers available too,
and Hickock fans needing repair or service can always mail Hickockdoc
for more details.
|Need manuals? Try
Crowthorne Tubes - http://www.crowthornetubes.com
They have manual
copies available, scanned manuals on CD
ROM, and accept PayPal. This is a part time outfit run for
enthusiasts rather than a big business - what a great find!
can do photocopy manuals from $15 for the CT-160 and a whole rack of
other tube testers too.
||Show on the left is an early advertisement for these testers, kindly
donated by Martin Ackroyd.
You can click on the picture to see the full size version.